Contrast-enhanced echocardiographic assessment of left ventricular wall measurements in cats

Hypertrophic cardiomyopathy (HCM) is defined by increased left ventricular wall thickness (LVWT), making accurate measurement essential. Contrast-enhanced echocardiography (C-ECHO) improves myocardial border delineation. We aimed to evaluate whether C-ECHO provides more reliable LVWT measurements in cats than standard echocardiography (S-ECHO).

Forty-five cats (32 with an LVWT <6 mm and 13 with an LVWT ≥6 mm) were prospectively enrolled in the study. Two-dimensional right parasternal short-axis images were acquired before and after contrast administration (SonoVue: 0.05 mL/kg [0.04-0.14 mL/kg]). Septal and posterior wall thickness values were measured using both modalities. Agreement and reliability were assessed using Bland-Altman analysis, Kappa statistics, and intraclass correlation coefficients.

Left ventricular wall thickness was greater with S-ECHO than C-ECHO (maximal LVWT: 5.0 mm [2.8-9.5 mm] vs. 4.2 mm [2.5-8.9 mm], P < 0.0001). On average, the LVWT measured by S-ECHO was 0.61 mm greater than that obtained by C-ECHO. Agreement between S-ECHO and C-ECHO for HCM diagnosis was only moderate (Kappa: 0.50). The Bland-Altman analysis showed fixed biases and wide 95% limits of agreement (LoA) for LVWT (septum: bias: 0.8 mm, LoA: -0.7-2.3 mm; posterior wall: bias: 0.4 mm, LoA: -1.1-2.0 mm). Contrast-enhanced echocardiography demonstrated higher measurement reliability (intraclass correlation coefficient: 0.99 vs. 0.96).

A low-mechanical index preset was not used, and measurements were not timed using an electrocardiogram (ECG).

Standard echocardiography seems to overestimate LVWT compared to C-ECHO, consistent with findings reported in human studies. Contrast-enhanced echocardiography improves measurement reliability. These findings support its use to enhance HCM assessment in cats.